1. Field of the Invention
The present invention relates to an apparatus for forming an alignment layer, and particularly, to a central supplying unit of an alignment material capable of rapidly performing processes and efficiently managing the alignment material by allowing an automatic supply of the alignment material from a central supplying unit to a plurality of alignment layer forming lines, and an apparatus for forming an alignment layer having the same.
2. Background of the Invention
Recently, various portable electric devices, such as mobile phones, personal digital assistant (PDA), and note book computers have been developed, because of their small size, light weight, and power-efficient operations. Accordingly, flat panel display devices, such as liquid crystal displays (LCDs), plasma display panels (PDPs), field emission displays (FEDs), and vacuum fluorescent displays (VFDs), have been developed. Of these flat panel display devices, the LCDs are currently mass produced because of their simple driving scheme and superior image quality.
FIG. 1 is a cross sectional view of an LCD device according to the related art. As shown in FIG. 1, an LCD device 1 comprises a first substrate 3, a second substrate 5 and a liquid crystal layer 7 interposed between the first and second substrates 3 and 5. Although not shown in the drawing, the first substrate 3 is a driving device array substrate which has a plurality of pixels, each of which is provided with a driving device such as a thin film transistor (FTF). The second substrate 5 is a color filter substrate which has a color filter layer for implementing actual colors. Also, each of the first substrate 3 and the second substrate 5 is provided with pixel electrodes and common electrodes, and coated with alignment layers for aligning liquid crystal molecules of the liquid crystal layer 7.
The first and second substrates 3 and 5 are bonded to each other by a sealing material 9. The liquid crystal layer 7 is formed between the first and second substrates 3 and 5 bonded to each other. With such configuration, the driving device formed at the first substrate 3 drives liquid crystal molecules to control an amount of light transmitted through the liquid crystal layer 7, thereby displaying information.
A fabricating procedure for an LCD device may be divided into a driving device array substrate process for forming a driving device on the first substrate 3, a color filter substrate process for forming a color filter on the second substrate 5, and a cell process. Such fabricating procedure for the LCD device will be described with reference to FIG. 2.
First, a plurality of gate lines and data lines arranged on the first substrate 3 to define pixel areas are formed by the driving device array process, and then a TFT as a driving device connected to the gate line and the data line is formed at each pixel area (S101). Also, a pixel electrode, which is connected to the TFT to drive the liquid crystal layer 7 according to a signal applied via the TFT, is formed through the driving device array process.
R, G and B color filter layers for implementing colors and common electrodes are formed on the second substrate 5 through the color filter process (S104).
After coating an alignment layer on each of the first and second substrates 3 and 5, the alignment layers are rubbed to provide an alignment controlling force or a surface fixing force (i.e., a pretilt angle and an alignment direction) to the liquid crystal molecules of the liquid crystal layer 7 formed between the first substrate 3 and the second substrate 5 (S102 and S105). A spacer is then dispersed onto the first substrate 3 for maintaining a uniform cell gap between the first and second substrates 3 and 5. A sealing material is coated on peripheral portions of the second substrate 5, and thereafter the first and second substrates 3 and 5 are bonded to each other by compressing (S103, S106 and S107).
In the meantime, the first and second substrates 3 and 5 are both made from a glass substrate, and include a plurality of unit panel areas on each of which the TFT as the driving device and the color filter layer are formed. So, in order to fabricate each liquid crystal panel, the glass substrate should be cut into unit panels and then processed (S108). Liquid crystal is injected into each of the processed liquid crystal panels through a liquid crystal injection hole, which is then encapsulated so as to form the liquid crystal layer. The thusly-completed liquid crystal panel is inspected to finally fabricate an LCD device (S109 and S110).
The LCD device having fabricated through those processes uses an electro-optic effect. The electro-optic effect is determined by anisotropy of liquid crystal molecule and a molecule arrangement state of liquid crystal molecules. Accordingly, the control of the liquid crystal molecule arrangement has a great influence on display quality of the LCD device. Hence, an alignment layer forming process for more effectively aligning liquid crystal molecules is very important in the fabricating procedure for the LCD device in relation to characteristics of image quality.
An alignment layer is formed by coating an alignment material on a substrate by means of a coating device. Here, a plurality of alignment layer coating devices are disposed on the process line for an LCD device and each alignment layer coating device is provided with an alignment material supplying unit so as to allow the supply of the alignment material to each of the alignment material coating device, thereby coating the alignment material on the substrate.
However, the alignment material coating device may occur the following problems. As the alignment material is coated on the substrate by the alignment material coating device, the alignment material contained in the alignment material supplying unit, through which the alignment material is supplied to each alignment material coating device, is decreased. When the alignment material in the alignment material supplying unit is completely consumed, the alignment material should be newly supplied into the alignment material supplying unit. In general, the alignment material supplying unit is provided with a supply tank and an alignment material container disposed in the tank for containing the alignment material. In order to supply the alignment material into the alignment material supplying unit, the alignment material container from which the alignment material has completely been consumed should be replaced by a new alignment material container fully filled with an alignment material.
However, the alignment material container is replaced by an operator himself, which requires long time to replace it and increased replacement cost. Furthermore, the plurality of alignment material coating devices are provided on the LCD device process line so as to coat alignment layers on a plurality of substrates at once. Accordingly, much time loss occurs upon replacing the alignment material containers of the plurality of alignment material supplying units provided at each alignment material coating device, thereby increasing the replacement cost. In addition, the supply of the alignment material into the alignment material supplying unit, namely, keeping, carrying and replacing of the alignment material container are all executed by an operator's own work, which causes a problem in the management of the plurality of alignment material containers.